Herbicidally active pyridyl-/pyrimidyl-pyrazine derivatives

Abstract

The present invention relates to herbicidally active pyridyl-/pyrimidyl-pyrazine derivatives, as well as to processes and intermediates used for the preparation of such derivatives. The invention further extends to herbicidal compositions comprising such derivatives, as well as to the use of such compounds and compositions in controlling undesirable plant growth: in particular the use in controlling weeds, in crops of useful plants.

The invention claimed is: 
     
       1. A method, comprising: applying as an hericide a compound of formula (I) 
       
         
           
           
               
               
           
         
       
       or a salt thereof, wherein:
 X 1  is N or CR 1 ; 
 R 1  is selected from the group consisting of hydrogen, halogen, cyano, C 1 -C 6 alkyl, C 3 -C 6 cycloalkyl, C 2 -C 6 alkenyl, C 2 -C 6 alkynyl, C 1 -C 6 alkoxy, —C(O)OC 1 -C 6 alkyl, —S(O) p C 1 -C 6 alkyl, NR 6 R 7 , C 1 -C 6 haloalkoxy and C 1 -C 6 haloalkyl; 
 R 2  is selected from the group consisting of halogen, cyano, nitro, C 1 -C 6 alkyl, C 1 -C 6 haloalkyl, C 2 -C 6 alkenyl, C 2 -C 6 alkynyl, trimethylsilylC 2 -C 6 alkynyl-, C 3 -C 6 cycloalkyl, C 5 -C 6 cycloalkenyl, —C(O)OC 1 -C 6 alkyl, —S(O) p (C 1 -C 6 alkyl), C 1 -C 6 alkoxy, C 1 -C 6 haloalkoxy, —O—(CR a R b ) q R 9 , or phenyl; 
 R 3  is selected from the group consisting of hydrogen, C 1 -C 6 alkyl, C 2 -C 6 alkenyl, C 2 -C 6 alkynyl, C 2 -C 6 haloalkenyl, C 1 -C 6 alkoxyC 1 -C 3 alkyl-, C 1 -C 6 haloalkyl- and —(CR a R b ) q R 5 ; 
 R a  is hydrogen or C 1 -C 2  alkyl; 
 R b  is hydrogen or C 1 -C 2  alkyl; 
 R 4  is hydrogen, C 1 -C 6 alkyl, C 2 -C 6 alkenyl, C 2 -C 6 alkynyl, C 2 -C 6 haloalkenyl, C 1 -C 6 alkoxyC 1 -C 3 alkyl-, C 1 -C 6 haloalkyl- and —(CR a R b ) q R 5 ; 
 R 5  is hydroxy, —C(O)OC 1 -C 6 alkyl, —C 3 -C 10 cycloalkyl, -aryl, or -heteroaryl wherein said aryl and heteroaryl are optionally substituted by 1 to 3 independent R 8 ; 
 or R 3  and R 4  together with the nitrogen to which they are attached, form a saturated or partially unsaturated 4-6 membered ring system optionally containing 1 or 2 further heteroatoms independently selected from S, O and N, wherein said ring is optionally substituted by 1 to 3 R 8 ; 
 R 6  and R 7  are independently selected from the group consisting of hydrogen, C 1 -C 6 alkyl and —C(O)OC 1 -C 6 alkyl; 
 each R 8  is independently selected from the group consisting of halogen, C 1 -C 6  alkyl and C 1 -C 6 alkoxy-, C 1 -C 6  haloalkyl, C 1 -C 6  haloalkoxy-, cyano and S(O) p (C 1 -C 6 alkyl); 
 R 9  is —C(O)OR c , —OC(O)R c , —C 3 -C 6 cycloalkyl, or an -aryl, -aryloxy, -heteroaryl, -heteroaryloxy or -heterocyclyl ring, wherein said ring is optionally substituted by 1 to 3 independent R 8 ; 
 R c  is hydrogen or C 1 -C 4 alkyl; 
 n is 0 or 1; 
 p is 0, 1, or 2; and 
 q is 0, 1, or 2. 
 
     
     
       2. The method of  claim 1  comprising the compound of formula (I), wherein X 1  is N. 
     
     
       3. The method of  claim 1  comprising the compound of formula (I), wherein X 1  is CR 1  and R 1  is selected from the group consisting of cyano, fluoro, chloro, methoxy-, difluoromethoxy, and trifluoromethyl. 
     
     
       4. The method of  claim 1  comprising the compound of formula (I), wherein R 2  is halogen, cyano, C 1 -C 4 alkyl, C 1 -C 4 haloalkyl, C 2 -C 4 alkenyl, C 2 -C 4 alkynyl, trimethylsilylC 2 -C 4 alkynyl-, —C(O)OC 1 -C 4 alkyl, —O—(CR a R b ) q R 9 , or phenyl. 
     
     
       5. The method of  claim 1  comprising the compound of formula (I), wherein R 3  and R 4  are each independently selected from the group consisting of hydrogen, C 1 -C 4 alkyl, C 2 -C 4 alkenyl, C 2 -C 4 alkynyl, C 2 -C 4 haloalkenyl, C 2 -C 4 alkoxyC 1 -C 3 alkyl-, C 1 -C 4 haloalkyl- and —(CR a R b ) q R 5 . 
     
     
       6. The method of  claim 5  comprising the compound of formula (I), wherein R 3  is hydrogen or methyl, and R 4  is selected from hydrogen, hydrogen, C 1 -C 4 alkyl, or —(CR a R b ) q R 5 . 
     
     
       7. The method of  claim 5  comprising the compound of formula (I), wherein R 5  is hydroxy, C 3 -C 6 cycloalkyl, phenyl or a 5-10-membered heteroaryl ring system, wherein said phenyl or heteroaryl ring system is optionally substituted by 1-3 R 8 . 
     
     
       8. The method of  claim 7  comprising the compound of formula (I), wherein R 5  hydroxy. 
     
     
       9. The method of  claim 1  comprising the compound of formula (I), wherein R 3  and R 4  together with the nitrogen atom to which they are joined, form a saturated or partially unsaturated 5- or 6-membered ring system optionally containing from 1 or 2 further heteroatoms independently selected from S, O and N, wherein said ring is optionally substituted by 1 to 3 independent R 8 . 
     
     
       10. The method of  claim 9  comprising the compound of formula (I), wherein R 3  and R 4  together with the nitrogen atom to which they are joined form a pyrrolinyl, pyrrolidinyl, pyrazolinyl, pyrazolidinyl, imidazolinyl, imidazolidinyl, triazolyl, piperidyl, morpholinyl, thiomorpholinyl, and piperazinyl ring, each optionally substituted by 1 to 3 independent R 8 . 
     
     
       11. The method of  1  with the proviso that the compound of formula (I) is not:
 (i) methyl 6-(5-methyl-3-pyridyl)-3-morpholino-pyrazine-2-carboxylate, or 
 (ii) methyl 3-amino-6-(3-pyridyl)pyrazine-2-carboxylate.